Suggestion for Twig 4: Change the `|default()` filter to respect `false`

[ThomasLandauer]

{{ false|default(true) }} gives true, since default() obviously treats false just like null or undefined.
It's documented at https://twig.symfony.com/doc/3.x/filters/default.html, but still weird ;-)

I just wanted to add this to the wishlist for Twig 4, but the thread at #3951 is already closed.

[felds]

@ThomasLandauer The ?? operator seems to do exactly that.

It's kinda confusing at first because ??, ?: are operators and and |default() is a filter, but they cover every combination I can think of:

{{ dump(I_DONT_EXIST|default('a0')) }}  {# "a0" #}
{{ dump(false|default('a1')) }}         {# "a1" #}
{{ dump(null|default('a2')) }}          {# "a2" #}
{{ dump(0|default('a3')) }}             {# 0 #}

{{ dump(I_DONT_EXIST ?? 'b0') }}        {# "b0" #}
{{ dump(false ?? 'b1') }}               {# false #}
{{ dump(null ?? 'b2') }}                {# "b2" #}
{{ dump(0 ?? 'b3') }}                   {# 0 #}

{{ dump(I_DONT_EXIST ?: 'c0') }}        {# "c0" #}
{{ dump(false ?: 'c1') }}               {# "c1" #}
{{ dump(null ?: 'c2') }}                {# "c2" #}
{{ dump(0 ?: 'c3') }}                   {# "c3" #}

[whataboutpereira]

BcMath\Number just came to bite me. It seems a Number of '0.00' is also considered empty while '0.00' as a string is not.

[felds]

@whataboutpereira take $n = new BcMath\Number('0.00').

$n behaves like 0 mathematically, so !$n == true.
"0" is a special case when converted to boolean. Any other non-empty string is evaluated as true, even "00".

So…

• $n is false
• (string)$n, "$n", printf('%s', $n) are all true